Blending of hydroformer feed stocks



/VET GAS March 18, 1952 B. B. WOERTZ ETAL 2,589,523

BLENDING oF HYDROFORMER FEED STOCKS Filed June 2l, 1948 Patented Mar. 18, 1952 BLENDING F HYDROFORMER FEED STOCKS Byron E. Viocrtz, Skokie, Lawrence M. Henderson, Winnetka, and Charles M. Ridgway, Crys- -tal Lake, Ill., assignors to The Pure Oil Comlpany, Chicago, Ill., a corporation of Ohio application .inne 21, 1948, Serial No. 34,276

'l Claims. 1

This invention relates to a process for producing aromatic hydrocarbons from naphthenic, parainic and olenic hydrocarbons and is more particularly concerned with a process for producing a high yield of alkylated benzenes.

It is well known in the art to convert naphthenic, oleiinic and paraninic hydrocarbons to aromatic hydrocarbons by contacting naphthenic, paraii'inic and/or olenic hydrocarbons with a dehydrogenation catalyst in the presence of hydrogen or hydrogen-bearing gas. This process is commonly known in the art as catalytic hydroforming and involves the contact of the charging stock with a dehydrogenation and aromatization catalyst in the presence of hydrogen or hydrogen-bearing gas at temperatures of approximately 850-1100 F., andat pressures of approximately 1D0-800 pounds per square inch, and preferably between 150-300 pounds per square inch. As catalysts in the process aluminum oxide in the form of activated alumina, bauxite, aluminum hydrate or aluminum gel containing approximately 1%20% byA weight of a metal oxide or sulde from the group of metals of the IV, V, VI and VIII grou'p of the periodic system is generally used. The catalyst may be made.

mina or peptized aluminum gel containing from v 1%20% by weight of molybdenum oxide or chromium oxide has been widely used in commercial operations. Other oxides or suldes which may be used to impregnato the aluminum oxide are those of vanadium, tungsten, and nickel.

We have discovered that if the ymiddle fraction of the naphtha stock which is charged to a conventional hydroforming operation is eliminated from the charge, an aromatic solvent rich in alkylated benzenes can be produced Without undue carbonization of the catalyst.

One of the objects of the invention is to provide an improved process for preparing aromatic hydrocarbons from non-aromatic hydrocarbons.

Another object of the invention is to provide a method for producing a high yield of aromatics without excessive coking of the catalyst.

A still further object of the invention is to provide a method for preparing a product suitable as a solvent which is rich in alkylatcd benzenes.

Other objects of the invention will be apparent from the following description and the accom panying drawing of which the single gure is a diagrammatic view of apparatus suitable for carrying out the invention.

Referring to the drawing, the numeral I i-ndicates a line through which a low end point naphtha is charged by means of pump 3 to heating coil 5. The numeral 1 indicates another line through which a high boiling range naphtha is chargedby means of pump 9 to heating coil 5. The low end point naphtha charged through line l preferably has an end point below 300 F., and preferably not above 250 F., and may have an initial boiling point rangingA from approximately 150-200 F. The high boiling naphtha fraction should have a minimum boiling point of approximately 325 F. and an end point not above approximately 550 F.; preferably it will lie Within the range of m-500 F. It is importantto charge a substantial portion of low end point naphtha in admixture with a high boiling fraction in order to prevent excessive coking ofthe catalyst. The amount of light naphtha which is preferably mixed with the heavy fraction ranges from fc-95% by volume of the total charge.

It will be apparent that instead of mixing a low end point naphtha with a high boiling range naphtha, a full boiling range naphtha may be fractionated by eliminating a middle portion Aboiling between the limits of approximately 250- 450" F., and remaining portion of the naphtha used as charging stock for the process.

We prefer to use as charging stock a high boil ing range naphtha which is rich in naphthene hydrocarbons since naphthene hydrocarbons are most readily converted to aromatics. I

The charging stock is heated in heating coil 5 to a temperature of approx'rnately @50% 1100 F., and preferably to a temperature of be-i tween 9001000 F., under a pressure of approximately 100-800 pounds per square inch, and

preferably at a pressure of -300 pounds per square inch. In starting up the process it may be advisable to charge hydrogen or gas rich in hydrogen through line II in an amount equal to approximately 250 mol per cent of the charging stock. The gas will be charged through line Il into heating coil 5 by means of compressor' I3. The heated reaction mixture passes through either catalytic reactors I4 and I5 or I6 and I1. Reaction'products are reheated in passing from first reactor I4 or I6 to second reactor I5 ork l1, respectively, by means of heating coil I 8 or I9, re spectively. One set of reactors will be on stream while the other is undergoing regeneration. The' reactors are lled with a dehydrogenation' and aromatization catalyst such as those previously mentioned. We prefer to use as' catalysts alumina gel, activated alumina or bauxite, each of which is impregnated or co-precipitated with ap` proximately 9% of molybdenum oxide such as catalyst marketed by Standard Oil Co. of California. In the reactors among the reactions which occur are the conversion of naphthney hydrocarbons to aromatic hydrocarbonsand'the paraffin hydrocarbons to olefins and aromatic hydrocarbons. Upon leavingthe catalytic reactor,

the reaction products are cooled in condenser 20 to a temperature of approximately 100 F., vand pass to separator 2| where they are separated into gas and liquid fractions. The liquid is withdrawn through line 22 and passes through heat exchanger 23 to a fractionating tower not shown, where it is separated into various cuts including a out boiling between approximately 325-375 F. Residual gas is withdrawn from the top of separator 2| through line 24 and compressed by means of compressor 25 to a pressure sufcient to force recycle gas back into the reaction system. The compressed gas passes into the lower part of absorber 26 wherein it is contacted with a descending stream of absorption oil. Rich oil leaves the bottom of the absorber through line -21, Vcontrolled by float-controlled valve 29 and passes through heat exchanger 3| into stripper 32, wherein pressure is reduced to approximately atmospheric and the oil is denuded of its absorbed constituents which leave the stripper throughY line 33. Lean absorption oil leaves the bottomv of thestripper through line 34 and is pumped by means of pump 35 through heat exchanger 3| and cooler 35 back to absorber 26. Unabsorbed gas is recycled from absorber 26 back to the system through line 31.

After operation of the process begins and gas is produced, the gas can be recirculated, and the injectionA of 'hydrogen through line Il stopped. Because the action which takes place in the ca talytic'reactors'l4, 15,' I6 and I1 is essentially one of dehydrogenation and aromatization, the gas recycled through line 31 will be rich in hydrogen. Y When the yield and character of the reaction products indicates that the catalyst is no longer effective, the Voperation is switched from one set of reactors to the other and the reactors taken oi stream may be ilushed with inert gas such as nitrogen, steam or combustion gases. After the reactors have been flushed to remove any volatile material, the catalyst is, regenerated by charging thereto diluted oxygen or air through line 39 by means of compressor 4| until the carbon or coke is burned off the catalyst. The rate of injection of air or oxygen is controlled so as not to cause the temperature during regeneration to rise above 1200 F. In order to control the temperature during regeneration, the air maybe diluted with inert gasV such as nitrogen, carbon dioxide, steam and/or Vspent burnout gas so that it contains from 0.5 to- V5.0% by volume of oxygen. The length of t-he regeneration periodand the length of the reforming period'will vary somewhat, but we have foundthat a cycle of six hours for reforming and six -hoursfor purging and regeneration give a satisfactory operating cycle.

During the primary burning out period, the fresh burnout gas passes through line 42 and either line 43 or 45 depending upon which set of reactors isbeing-regenerated.r Valves 46 and 41 areA closed.'v By-pass lines 48 and 49 are provided around heating coils I8 and I 9,'respectively, so that regeneration gases can by-pass around the heaters." Regeneration products leave the reactors through either line |l or 53. A portion of the gas iseliminated from the system through line '55; .The remainder of the gas is recycled through waste'heat boiler 56 by means of compressor 51 and through heater 53 for dilution of incoming air. While not shown in the drawing, provision is ordinarily made for separately regenerating each reactor, rather than in series.

if The reactors'undergoing regeneration are generally subjected to a secondary burn out by reversing the gas flow therethrough. By opening valves 46 and 41 and closing valves 6| and 62, burnout gas is caused to flow through by-pass line 63 and then forced by compressor 51 through by-pass line 65 and line 61 into the bottom of second reactor |5 or |1.

It will be apparent from the arrangement of lines and valves in the drawing that one set of reactors can be maintained on stream while the other set is being regenerated. l

In order to demonstrate the invention, a series of runs were made using different charging stocks, some of which contained middle boiling range naphtha and some of which were devoid of'middle range naphtha. The runs were all made in a pilot plant using Standard Oil Company of California catalyst and the conditions under which the runs were performed and the results obtained are tabulated in the following Table I:

TABLE I- Rnn No 68 73 69 70 71 72 Time on Stream (Hours). 6 6 6 6 6 G Charge:

viii' liierhcnfits'erfm ssl/g s l/g ap t a 06 3 331 10 10 25 Vol. Per Cent st. run

Naphtha 315-400 F. 33% 33%- 0 15 0 0 Vol. Per Cent st. run

Naphtha -299 F. 33% 33% 66% 75 90 75 Reaction Pressure, p'. s. i. 227 235- 224 233 229 233 Average Reaction Temperature, F 940 940 040 942 940 942 Space Ve10oity,V/Hr./V 0.442 0.450 0. 44S 0.446 0.445 0.445 H2 in recycle gas (Volume l Per Cen 74. 1 83. 2 68. 6 85.0 88. 4 81. 0 Yield-Weight Per Cont Feed (No loss basis v Gas 34. 92 30.00 29.18 33.83 Liqui 63.05 68.91 69. 91 64. 92 Coke 2. 03 l. 09 0, 91 1. 25 Gravity API (calculated) of debutanized hydroformate 43. 5 44. 2 45. 4 47.5 48. 3 4S. 0 Yield (Weight Per Cent of feed) of 325-375 F. fraction 8.84 9. 7l 4. 54 5. 28 3. 24 3. 48 Properties of 325-375 F.

product: A. P. Gravity 36. 2 37.0 31. 6 32.8 31 2 32. 2 Bromme No 1.0 1. 5 l. 2 0. 9 1 0 1.4 Volume Per Cent 01cns...V 0.9 1.4 1.1 0.8 0.9 1.3 Volume Per Cent alkylated benzenes 73 70 93 S7 96 91 Mixed Aniline Point:

C-. 33. 8 34. 8 20. 6 24.0 18.0 2. 6 F 92. 8 94. 6 v 69. 1 75. 2 64. 4` 72. 7

The properties of the several fractions used as charging stock are given in the following Table II:

TABLE II Charge stock properties of Mid-Continent straight run naphthas 1 406- 315- 190- Tramo 496F. 400F. 299F.

Properties:

API Gravity 41. 8 47. 6 60.3 ASTM Distillation:

IBP, "F 406 315 190 419 330 202 422 834 204 430 346 210 441 355 218 454 365 230 476 380y 254 486 390 271 496 400 299 Percent Loss 0. 5 0. 8 1.1 Mixed Aniline Point, oF 143 138 143 Bromine Number 1.2 i 0.7 Volume Percent Olens. 0. 9 1.1 0. 5 Volume Percent Aromatics 14. 6 l5 4. ASTM mm. Octane 52. 2 i Y equal parts of low end point, middle range and high boiling range naphtha, the aromatic content of the 325-375 F. portion of the product was low, being of the order of 73% and 70% by volume, respectively. On the other hand, where the charging stock contained no middle range naphtha, such as the charge in runs 69, 7l and 72, the aromatic content of the 325-375 F. fraction was uniformly high, being above 90% in each case. The effect of eliminating the middle range naphtha is pointed up by a comparison of runs 73 and`69, and by a comparison of run 70 with runs 71 and 72. By substituting low or high boiling range naphtha for middle boiling range naphtha, the concentration of alkylated benzenes in the 325-375 F. fraction is very materially increased. It is notable that the 325- 375 F. fraction is Very low in olens as indicated by the, bromine number. This fraction of the reaction product is composed chiefly of alkylated benzenes which may be separated into substantially pure aromatic hydrocarbons by suitable fractionation methods or which may be used as an aromatic solvent. The presence in the charging stock of benzenoid hydrocarbons boiling Within the middle naphtha boiling range is not objectionable because the benzenoid hydrocarbons pass through the process without substantial alteration. Hence, recycling of hydroformed material within this range may be practiced Without materially detracting from the process.

By charging a blend of a low boiling fraction with a high boiling fraction, or by eliminating a Note particularly run 69 where the yieldof alkylated benzenes was 3.71%, a figure considerably in excess of the yield obtained in any of the runs numbering 60-64, inclusive, in which the charge was either 100% high boiling -fraction or 100% low boiling fraction.

It will be seen, therefore, that in accordance with our invention not only is it possible to obtain a high concentration of alkylated benzenes in the reaction product, but the yield of alk'ylated benzenes obtained is greater than can be obtained by charging either the high boiling or 10W boiling fraction alone.

What is claimed:

l. The method of preparing alkylated benzene hydrocarbons comprising, contacting a mixture of vpredominantly paraflinic `and naphthenic hy` drocarbons consisting substantially entirely of4 two fractions of virgin naphtha boiling Within the ranges of 190 to 300 F. and 400 to 500 F., With a dehydrogenation catalyst in the presence of hydrogen under substantial pressures exceed.

ingatmospheric and at temperatures of approximately 850 to 1100" F.

-2. The method in accordance with claim 1 in which the catalyst is a combination of a highly porous form of alumina and molybdena.

3. The method in accordance with claim 1, in which the hydrocarbon charge is made up ofr fractions in the two boiling ranges of substantially equal volume.

4. The method in accordance with claim 1 in which the hydrocarbons contacted with the catalyst consist of a mixture of 10 to 331/3 per UNITED STATES PATENTS Number Name Date 2,313,117 Becker Man 9J 1943 .Conversion of Petroleum, by Sachanen, 1st 2,328,773 Benedict Sept 7, 1943 F 6111151011, 1940, RenhOl'd Publishing CDTI). New 2,333,573 creelman Jan.. 4, 1944 0 York page 173- 2,375,573 Meier May 8, 1945 middle boiling fraction from a composite charge, cent by volume of straight-run naphtha boilingv the yield of alkylated benzenes over that which between approximately 400 to 500 F., and 90 can be obtained from charging either a high boiltio 66% per cent by volume of straight-run ing or low boiling fraction is increased, thereby nanhtha boiling between approximately 190 to obtaining an unexpected result. This increase 300 F. in yield from the blend of the high boiling and BYRON B. WOERTZ. low boiling fraction is demonstrated by a com- LAWRENCE M. HENDERSON. parison of the results in the following Table III: CHARLES M. RIDGWAY.

TABLE III Run No 09 71 72 00 04 01 02 03 Feed Composition, Volume Percent:

40049011* 33% 10 25 0 0 100 100 100 31540oF o 0 0 0 o 0 0 0 i-299F 00% 90 75 100 10o 0 0 0 Average ReactionTemp.,F 940 940 942 941 949 943 946 943 Volume Per cent Debutanized l Hydroormate on charge, No lossbasis 00. 30 00.23 02.41 05.91 72.90 00.47 09. 04 07.44 Alkylated Benzene Concentration in 325-375 F., Volume Per cent 93 96 91 98 96 97 96 90 Yieldton Charge, Volume Perceg2g-.175 F. column Head Fraction a. 99 2.77 3.05 1.01 1. 5a 2.2.9 2.44 3.00 AlkylatedBenzenein325 f A- 375F.Frac1i0n 3. 71 2. 00 2. 7s 1. 5s 1.47 2.32 2.34 2. 70 API Gravity of 525-375 F.

Fraction 31.0 31.2 32.2 30.1 30.4 31.2 30.4 32.1

REFERENCES CITED Number Name Date The following references are of record in the 2392398 McMillan et al' Jan' 8' 1946 fue of patent: V1.) Aug- 20| OTHER REFERENCES Newton Aug. 27, 1946 

1. THE METHOD OF PREPARING ALKYLATED BENZENE HYDROCARBONS COMPRISING, CONTACTING A MIXTURE 